The invention relates to a camera system including a replaceable lens, and an image forming apparatus.
A camera system including a replaceable lens may use a contrast auto focusing (AF) method in order to adjust a focal point. The contrast AF method may include calculating an AF estimation value with respect to an image signal generated by an imaging device, detecting the focal point from the AF estimation value and then driving a focus lens.
In detail, in the contrast AF method, a point of time at which the imaging device captures an image corresponds to a lens location. In addition, a point of time at which an AF estimation value is maximized is detected from changes in the AF estimation value generated from image signals that are continuously generated. An AF operation is performed by calculating a lens location corresponding to the detected point of time and then driving a lens to the calculated lens location.